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A013931 a(n) is squarefree and sum of all squarefrees <= a(n) is squarefree. 4
1, 2, 3, 5, 6, 10, 13, 15, 19, 22, 26, 30, 31, 35, 38, 39, 41, 43, 51, 55, 59, 65, 66, 67, 69, 70, 73, 74, 78, 79, 82, 85, 86, 89, 93, 95, 97, 102, 103, 105, 110, 111, 113, 118, 122, 123, 129, 130, 131, 133, 134, 137, 139, 142, 143, 145, 149, 154, 155, 157, 159, 163, 166, 167 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

MATHEMATICA

Module[{nn=200, sf}, sf=Select[Range[nn], SquareFreeQ]; Transpose[ Select[ Thread[ {sf, Accumulate[sf]}], SquareFreeQ[Last[#]]&]][[1]]] (* Harvey P. Dale, Feb 09 2013 *)

CROSSREFS

Cf. A005117, A013930, A013932.

Sequence in context: A241829 A250179 A202823 * A018429 A035953 A195054

Adjacent sequences:  A013928 A013929 A013930 * A013932 A013933 A013934

KEYWORD

nonn

AUTHOR

Henri Lifchitz

EXTENSIONS

More terms from David W. Wilson

STATUS

approved

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Last modified July 22 21:14 EDT 2019. Contains 325226 sequences. (Running on oeis4.)